This research program is concerned with regulation of secretory protein synthesis in exocrine glands, and changes in the regulatory mechanism during aging. The immediate goal is to determine whether secretory protein synthesis is regulated at the level of transcription or translation. In rat parotid glands, changes in rates of secretory protein synthesis in relation to aging, secretory (discharge) activity and varying levels of glucocorticoids accompany parallel changes in translational activities of total messenger RNA (mRNA) and mRNA specific for amylase, a major secretory protein of the gland. It is unknown if the changes in messenger activities are due to actual changes in the amount of mRNA involving regulation at the level of transcription. Quantitations of mRNA specific for secretory protein are possible using a cloned amylase complementary DNA (cDNA) probe, since amylase makes up a large proportion of the secretory proteins in parotid glands. cDNA clones, pucg, containing copies of salivary amylase sequence at pst 1 sites have been provided for this study by Dr. Miriam H. Meisler of this University. Specific aims are: 1. To establish technical procedures for amylase cDNA probe generation and hybridization for quantitation of amylase mRNA by dot blot and northern blot analyses. 2. To test the feasibility of applying the above techniques to determine if the increased rate of amylase synthesis following stimulated secretion of stored secretory proteins is accompanied by a parallel increase in the amount of amylase mRNA.